Control device



Jan. 11, 1955 R. R. PEES 2,699,161

CONTROL DEVICE Filed March 14, 1951 1N VEN TOR. P004420 9. P555 HIS 14TTUPN E Y8 United States Patent CONTROL DEVICE Ronald R. Pees, Dayton,Ohio, assignor to General Motors Corporation, Detroit, Mich., acorporation of Delaware Application March 14, 1951, Serial No. 215,572

4 Claims. (Cl. 123-198) This invention relates to a control deviceparticularly designed for use with diesel engines.

It is among the objects of the present invention to provide a controldevice for diesel engines effective to stop the engine upon failure ofthe lubricating system of the engine.

A further object of the present invention is to provide a control devicefor diesel engines which, if the pressure in the lubricating oil systemof the engine fails to reach a predetermined safe value after the enginehas operated for a period ordinarly suflicient to have the lubricatingoil pressure build up to said value, will automatically stop engineoperation.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to the accompanyingdrawing, wherein a preferred embodiment of the present invention isclearly shown.

In the drawing:

The simple view in the drawing illustrates schematically the electriccircuits and devices for operating and protecting a diesel engine.

Diesel engines are equipped with means operative to stop the engine. Inthe present drawing, an air box damper is shown operative by anelectromagnet to shut off combustion air to the engine for purposes ofstopping it. This air box damper is of the standard design and isapplied to the engine in the customary manner. The present drawingdiagrammatically shows this damper 20 and its electromagnet coil 21.

Various protective devices are provided on diesel engines which areeffective to stop the engine under unusual and what may be damagingcircumstances. A diesel engine generally has an overspeed governor whicheffects operation of the air box damper to stop the engine when itsspeed exceeds a predetermined rate. A normally open switch is alsoprovided, closable at predetermined temperature of the water in theengine cooling system to effect actuation of the air box damper forstopping the engine to prevent its operation when the cooling waterthereof exceeds a certain safe value. Another switch, normally closed,is operative by a predetermined lubricating oil pressure to open andrender the air box damper inoperative when a safe lubricating oilpressure is attained. Still another, normally open switch is provided,which is closable by a predetermined fuel oil pressure to complete itsportion of the circuit to the air box damper when the fuel oil pressurereaches a predetermined value.

Inasmuch as the present invention is directed primarily to engineprotection when failures occur in the lubricating oil system, theoverspeed governor and water temperature responsive devices will not beconsidered.

Ordinarily diesel engines equipped with air box damperselectromagnetically actuated to stop engine operation and lubricatingoil and fuel oil pressure switches for controlling the air box damperoperate in the following manner.

In starting a diesel engine, the fuel oil pressure switch 25, comprisingstationary contacts 26 and 27, connectible in series with the magnetcoil 21 of the air box damper 20 is adapted to be bridged and connectedtogether by the movable contact 28. Contact 28 is yieldably urged out ofengagement with its cooperating stationary contacts 26 and 27 and ismoved to engage them by any suitable means 29 actuated by the fuel oilpressure when it reaches a predetermined value for instance 20 poundsper square inch. The lubricating oil switch 30 is similar to switch 25but is normally closed so that its stationary contacts 31 and 32 areengaged by the movable, bridging contact 33. When the lubricating oilpressure reaches a predetermined pressure, for instance ten pounds persquare inch, element 34 is actuated by said oil pressure to move contact33 out of engagement with its cooperating contacts 31 and 32 and thusopen the circuit through the electromagnet 21 of the air box damper 20with which contact 31 is connected.

As shown in the drawing, contact 32 is connected with contact 27 andcontact 26 with one side of battery 40, the other side of the batterybeing connected with the air box damper coil or magnet winding 21.

In a diesel engine so equipped, switch 25 generally closes atsubstantially twenty p. s. i. fuel oil pressure and switch 30 atsubstantially ten p. s. i. lubricating oil pressure. Switch 30 is closedwhen the lubricating oil pres sure is less than the predetermined safeminimum and thus with switch 25 closed by the predetermined fuel oilpressure, the circuit through the air box damper magnet winding 21 iscompleted, causing energization of said magnet winding and operation ofthe air box damper to stop engine operation due to a dangerously lowlubricating oil pressure.

Under certain conditions, the fuel oil pressure reaches its requiredtwenty p. s. i. to close switch 25 before the lubricating oil pressurebuilds up to the required ten p. s. i. to open switch 30. In thisinstance, with both switches 25 and 30 closed, the air box dampercircuit is completed and the air box damper thus activated to stop theengine prematurely, inasmuch as the lubricating oil pressure, althoughbuilding up slowly, did not reach its required value to open switch 30before the air box damper became effective to stop the engine. Suchoperation is unsatisfactory, especially if occurring repeatedly, forsafe engine operation may obtain as long as the lubricating oil pressurebuild-up does not require excessively long engine operation.

The present invention eliminates this premature engine stoppage, due toslow build-up of lubricating oil pressure by providing a time delayrelay or circuit controller 50 in the circuit of the electromagnet 21 ofthe air box damper 20. This relay 50 consists of a pivoted frame 51 towhich the magnet winding 21 is electrically connected said frame beingpivoted to the stationary pin 51a. One end of a thermoelectric element52 is electrically and mechanically attached to a protruding ear 53 ofthe frame 51, the other end of said element being attached to anadjustable nut 54 carried by an insulated bracket of the relay. Nut 54is electrically connected to the contact 31 of switch 30, thusconnecting the thermoelectric element in series with the magnet winding21 of the air box damper 20 and switch 30. Element 52 is of sufficientresistance to current flow that it retards or substantially preventsenergization of the magnet winding 21 when its circuit is completedthrough said element 52. Another characteristic of element 52 is thatwhen cold, or particularly when not heated by current flow therethrough,it contracts and exerts a tension upon the frame portion 53 to move theframe counterclockwise as regards the drawing against the counteractingeffort of spring 55 to move the frame 51 clockwise about the pivot pin51a.

Frame 51 supports a resilient blade 56 at one end, the other end of saidblade extending beyond the end of the frame and carrying a contactelement 57 which is adapted to cooperate with stationary contact 58 alsoelectrically connected to contact 31 of switch 30. An insulated stop 59is engageable by blade 56 when contact 57 is held out of engagement withits cooperating contact 58. This occurs when element 52 predominates,being contracted and overcoming the turning effect of spring 55 to causecontact engagement. A resilient finger 60 has one end attached to orformed integral with the blade 56 adjacent contact 57, said finger beingbiased when its other end is seated in the V-shaped notch 61 in the endedge of frame 51.

When on the one side of blade 56 as shown in the drawing, the seatingpoint of finger 60 with the V-notch 61 of frame 51 causes the bias ofthe finger 60 to urge blade 56 into resting engagement with stop 59.This is under the influence of the retracted and dominatingthermoelectric element 52. When said element is heated and expands dueto a. continued current flow therethrough, the spring 55 becomeseffective to move frame 51 clockwise about its pivotal support therebyshifting the seating contact of finger 60 with notch 61 of lever 57 tothe opposite side of blade 56 so that the biasing effect of the finger60 upon blade 56 is reversed, the blade being shifted from engagementwith stop 59 into the position in which contact 57 on the blade engagescontact 58 connected to switch 30. This establishes a shunt circuitabout element 52 and thereby removes the coil 21 impeding resistancefrom the circuit through said coil, permitting energization of said coil21 and operation of the air box damper 20 to stop the engine, providedboth switches 25 and 30 are closed.

Thus the unsatisfactory condition resulting from the usual equipment andinvolving repeated engine stoppage due to abnormally slow build-up ofthe lubricating oil pressure after the engine has started to operate isavoided, for the time delay relay lengthens engine operation under theseconditions to a safe maximum, providing an additional interval for thelubricating oil pressure to build up to the predetermined value and openthe switch 30 to render the engine stopping device ineffective withoutendangering the engine. This additional interval is equal to the timerequired for element 52 to become sufficiently heated and consequentlyexpand sufficiently as to permit the spring 55 to become effective andcause closing of t the substantially unresisting current flow shuntcircuit across contacts 57 and 58 thereby to render the air box damperactive.

In case of complete lubricating oil pressure failure, switch closes andcompletes its circuit connection. The extra interval provided by thetime delay relay as aforedescribed would not extend operation of theengine beyond a safe limit even in case of complete failure oflubricating oil pressure.

From the aforegoing it may be seen that the present invention provides acontrol and protective device for a diesel engine, said devicemaintaining engine operation for a safe interval to give an abnormallyslow lubricating oil pressure build up an opportunity to reach itspredetermined value during the lengthened safe operation of the engine,failure of the lubricating oil pressure to reach said predeterminedvalue during engine operation resulting in action by the relay toenergize the engine stopping device and render it effective to stop theengine before lack of lubricating oil pressure may cause damage.

While the embodiment of the present invention as hereis disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted. W

What is claimed is as follows:

1. In a control device for an internal combustion engine having fuel andlubricating oil pressure lines and an electromagnetically actuateddevice for stopping the engine, the combination with an electric powercircuit connected to said device, of separate and independently actingswitch means in said power circuit, one of said means being normallyopen and operative for completing said circuit in response to apredetermined pressure in the fuel line and the other being normallyclosed and operative for opening said circuit in response to apredetermined pressure in the lubricating oil line; and a relayoperative only when said other means is closed, said relay having athermoelectric element connected in the power line between said othermeans and said device providing electrical resistance therein to preventenergization of the engine stopping device connected in the powercircuit therewith, said relay having another electrical conductingelement normally disconnected from the power circuit but operative toestablish a shunt circuit around said thermoelectric element in responseto action of said thermoelectric element due to current flowtherethrough for a predetermined interval, whereby the resistance of thethermoelectric element is circumvented and the said device is energizedthrough the shunt circuit to effect stopping of the engine.

2. In a control device for an internal combustion engine having fuel andlubricating oil pressure lines and an electromagnetically actuateddevice for stopping the engine, the combination with an electric powercircuit connected to said device, of normally open control means in saidpower circuit operative for completing said circuit in response to apredetermined pressure in the fuel line and normally closed controlmeans operative for opening said circuit in response to a predeterminedpressure in the lubricating oil line; and a time delay circuitcontrolling device in the power circuit with the aforesaid controlmeans, said control device having dual current flow circuit meanscomprising a thermo-electric element in the power circuit effectingsuflicient electrical resistance to prevent the energization of theengine stopping device and after a predetermined interval of currentflow therethrough effecting closing of the other normally open means insaid control device to establish therethrough a substantially unresistedcurrent flow through the power circuit around the said element wherebyto energize the engine stopping means to stop the engine.

3. in a control device for an internal combustion engine having fuel andlubricating oil pressure lines and an electromagnctically actuateddevice for stopping the engine, the combination with an electric powercircuit connected to said device, of two pressure actuated switchesconnected in series in said power circuit, the first of said switchesbeing normally open, but operative at a predetermined pressure in thefuel line, to close the circuit, the second being normally closed, butoperative at a predetermined pressure in the lubricating oil line toopen the power circuit; and a time delay relay including a resistanceelement in series connection in the power circuit between said secondswitch and said device to prevent energization of theelectromagnetically actuated engine stopping device when both of saidpressure actuated switches are closed, and a normally open circuitcontrol means electrically in parallel with the resistance element andactuated thereby after a predetermined interval of current flowtherethrough to effect closing of said control means to shunt theresistance element and thereby effect energization of the enginestopping device.

4. In a control device for an internal combustion engine having fuel andlubricating oil pressure lines and an electromagnetically actuateddevice for stopping the engine, the combination with an electric powercircuit connected to said device, of two pressure actuated switchesconnected in series in said power circuit, the first of said switchesbeing normally open, but operative at a predetermined pressure in thefuel line, to close the circuit, the second being normally closed, butoperative at a predetermined pressure in the lubricating oil line toopen the power circuit; and a time delay relay including two parallelcircuits in the power line, the first, through a thermo-electric elementin the circuit of the engine stopping device and of sufldcientresistance to prevent the energization of said device, the second,through two normally disengaged contacts operative under the effect ofexpansion of the thermoelectric element after a predetermined intervalof current flow therethrough, to establish a substantially unrestrictedflow of current through the engine stopping device to render it activewhen both pressure actuated switches are closed.

References Cited in the file of this patent UNITED STATES PATENTS2,010,960 Porque Aug. 13, 1935 2,061,164 McNeil Nov. 17, 1936 2,210,044Schirokauer Aug. 6, 1940 2,373,735 Alexander Apr. 17, 1945 2,410,998Reavis Nov. 12, 1946 2,418,235 Menzies Apr. 1, 1947 2,423,728 Ray July8, 1947 2,428,095 Reavis Sept. 30, 1947 2,428,909 Werner Mar. 2, 19482,565,984 Newman et al Aug. 28, 1951

